Dependence of RNA and protein synthesis on electrolyte concentrations

Abstract

Insects in diapause are in a state where development and RNA and protein synthesis are arrested; chilling breaks the diapause and induces synthesis. Initiation of development may be followed by altered permeability, hence a role of electrolytes is envisaged. In fact, Na +, K +, and Mg 2+ induced RNA and protein synthesis greatly in wings and to a lesser extent in fat body in the diapaused pupae of the silkworm, Hyalophora cecropia. The electrolyte concentration for peak synthetic activity varied and was 120, 40, and 100 m M for NaCl, KCl, and MgCl 2 respectively. Osmotic pressure effects of these elctrolytes, employing freezing-point depression values, were compared with the effect of the non-electrolytic, sucrose. The results indicated that Na + or Mg 2+ but not K + may act via positive osmotic pressure.